首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Solvent effects on the reaction equilibrium of the 1‐dodecene hydroformylation in a decane/N,N‐dimethylformamide solvent system is investigated. The reaction was performed at different decane/N,N‐dimethylformamide ratios and at temperatures between 368 K and 388 K. The equilibrium concentrations of all reactants and products were determined experimentally. The enthalpy and Gibbs energy of this reaction at the ideal‐gas standard state were determined by quantum‐chemical calculations in good agreement with literature data. Moreover, quantum‐chemically calculated standard Gibbs energies of reaction at infinite dilution in liquid decane/DMF‐solvent mixtures allowed a qualitative prediction of the solvent effect on the equilibrium concentrations. Based on the standard Gibbs energy of reaction at the ideal‐gas standard state and on fugacity coefficients calculated using the Perturbed‐Chain Statistical Associating Fluid Theory, the equilibrium concentrations of reactants and products for the 1‐dodecene hydroformylation performed in decane/N,N‐dimethylformamide mixtures of different compositions could be predicted in very good agreement with experimental data. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4576–4585, 2017  相似文献   

2.
Tunable solvent systems provide optimal reaction conditions for homogeneous catalysis as well as appropriate conditions for separating the product from the catalyst via temperature switches. Two tunable solvent systems are presented based on different thermodynamic concepts, namely thermomorphic multicomponent solvent systems and dispersions of immiscible liquids, stabilized by nonionic surfactants as microemulsions. Both systems were applied for the regioselective hydroformylation of the model substrate 1‐dodecene with a Rhodium/ligand catalyst system. The accessibility of the catalyst for the reactants was compared between the molecularly dispersed mixtures and the colloidally dispersed microemulsion systems which are heterogeneous on the microscopic level.  相似文献   

3.
The challenging task of homogeneous catalysis is the efficient combination of reaction and catalyst recycling. In the hydroformylation of long-chain olefins generally cobalt-based catalysts are used, but in our investigation we used rhodium-based catalysts, because of their higher activity in comparison to cobalt catalysts. In hydroformylation reactions, the recycling of the expensive rhodium catalyst as well as the selectivity to linear aldehydes are very challenging. Multiphase systems offer the possibility to increase the interfacial area during reaction on the one hand and to separate the metal–ligand complexes easily from the organic product phase after reaction, to recycle the expensive catalyst for further reactions, on the other hand. Solubilisers such as surfactants or polar solvents can be used to formulate such a tuneable solvent system. Upon cooling of the reaction mixture, phase separation is achieved. Based on that combination of reaction and phase separation for catalyst recycling, a novel process concept was developed for the hydroformylation of long-chain olefins. In order to show the applicability of that concept in a continuous process a fully automated miniplant was designed.  相似文献   

4.
In two case studies, the reaction performance of the aqueous biphasic hydroformylation of two industrially relevant oleochemicals, namely methyl 10‐undecenoate (case 1) and methyl oleate (case 2), is significantly improved by the use of a Jet‐Loop Reactor concept. Based on previously reported studies, only the two green and benign co‐solvents, 1‐butanol and isopropanol are applied, respectively, in the absence of any additional auxiliary. Both reactions benefit highly from using this special piece of equipment, specifically designed for improving gas–liquid–liquid mixing to create large interfacial areas with no moving internals. In case 1, the loading of the co‐solvent 1‐butanol is successfully reduced. For the first time significant yields (>40% after 1 h) are obtained in the absence of any co‐solvent, which is very beneficial, since aldehyde products and substrate form a pure product phase enabling straightforward separation. In case 2, the loading of the substrate methyl oleate is successfully increased from 6 to 30 wt% still showing satisfying productivity. At 15 wt%, the yield of the desired internal aldehydes in the jet‐loop reactor is increased by a factor of five compared to a stirred tank reactor after 3 h. Practical Applications: The production of aldehydes from hydroformylation of olefins is highly relevant for the chemical industry, since these can undergo numerous subsequent reactions, to form for instance alcohols, amines, and carboxylic acids. Generally, aldehydes from oleochemicals can serve as platform chemicals for gaining access to bifunctional molecules, which are interesting as polymer precursors. Performing hydroformylation with a water‐based solvent system enables efficient product separation from the aqueous catalyst phase for the realzation of more sustainable processes. By using the Jet‐Loop Reactor, the performance of the reaction system can be greatly improved addressing its practical relevance.  相似文献   

5.
Hydroformylation with Water- and Methanol-soluble Rhodium Carbonyl/phenyl-sulfonatoalkyl-phosphine Catalyst Systems – A New Concept for the Hydroformylation of Higher Molecular Olefins The heterogenization of the homogeneous hydroformylating catalyst system enables the recovery of the catalyst from the reaction products by a simple phase separation but it is unfavourable that many advantages of the homogeneous catalysis are given up by this procedure. To avoid this drawback we used rhodium carbonyl/tert. phosphine catalyst systems soluble as good in methanol as in water for the homogeneously catalyzed hydroformylation of the olefin in methanolic solution. Only after reaction the product mixture is heterogenized by adding water forming an aqueous phase containing the catalyst system. It was shown by the hydroformylation of n-tetradecene-1 with rhodium carbonyl/phenyl-sulfonatoalkyl-phosphine catalyst systems that this new conception is very useful for the oxo reaction of high-molecular olefins.  相似文献   

6.
Long chain olefins are converted into aldehydes by hydroformylation using synthesis gas CO/H2 and further converted in an acid‐catalyzed conversion with glycerol in a one‐pot procedure. Yields are up to 95 %. The obtained mixtures of 5‐ and 6‐membered rings are potential fuel additives offering alternative use of glycerol from renewable resources. By optimization of reaction conditions such as catalyst precursor, ligand, pressure, temperature, solvent or catalyst/substrate ratio a highly selective hydroformylation towards linear acetals was achieved. For synthesis of larger amounts, glycerol was converted with alkenes on a 2‐L‐scale and with aldehydes on a 60‐L‐scale.  相似文献   

7.
The biphasic hydroformylation of 1‐octene using a lean aqueous phase as solvent phase for catalyst recycling is discussed here. The gas‐liquid‐liquid reaction was homogeneously catalyzed by industrial standard catalytic system with [Rh(cod)Cl]2 as precursor and TPPTS as ligand. This work summarizes investigations addressing different aspects of the reaction, where a procedural approach was followed to gain understanding of its nature, kinetics and interphase reactivity. Finally, the application of the jet loop reactor is analyzed as a means to intensify the reaction.  相似文献   

8.
氢甲酰化反应是目前生产醛醇化合物最重要的反应之一,高碳烯烃氢甲酰化工艺改进是研究的难点和热点之一。探索了一种C10烯烃氢甲酰化反应的工艺,以三苯基膦(Ph3P)和亚磷酸三(2-叔丁基-4-甲氧基苯基)酯(LA)混合物为配体,与乙酰丙酮二羰基铑原位合成的催化体系催化1-癸烯氢甲酰化反应。系统考察了反应温度、反应压力、铑浓度、膦铑比、无机盐添加剂对反应的影响。结果表明,在n(Ph3P)/n(LA)=10、铑质量分数为280 mg/kg,1-癸烯用量(相对于甲苯)为0.3 g/mL,n(膦)/n(铑)=45、反应温度为90 ℃、反应压力为2.0 MPa、n(一氧化碳)/n(氢气)=1条件下反应4 h,1-癸烯转化率为98.1%、醛收率为93.2%、正异比为7.5。研究还发现,在减压蒸馏产物与催化剂分离时,加入无机盐添加剂能够提高催化剂的稳定性,减少铑损失。  相似文献   

9.
The kinetics of a gas–liquid reaction, alkene hydroformylation was studied in the presence of a homogeneous catalyst in a pressurised laboratory‐scale semibatch reactor. Hydroformylation of propene to isobutyraldehyde and n‐butyraldehyde was carried out at 70–115°C and 1–15 bar pressure in 2,2,4‐trimethyl‐1,3‐pentanediol monoisobutyrate solvent with rhodium catalyst using the ligands cyclohexyl diphenylphosphine. In order to evaluate the influence of mass transfer, experiments were made using varied stirring rate from 100 to 1000 rpm at 100°C and 10 MPa syngas pressure. Only at higher stirrings rates, the reaction took place in the kinetic regime. A reactor model was developed comprising both complex kinetics and liquid‐phase mass transfer. The model was based on the theory of reactive films. The model is able to predict under which circumstances the hydroformylation process is affected by liquid‐phase diffusion of the reactants. Experimental data and model simulations are presented for the hydroformylation of propene in the presence of a homogeneous rhodium catalyst.  相似文献   

10.
The combination of calixarene‐derived surfactants and neutral rhodium complexes containing a hemispherical “1,3‐calix‐diphosphite” ligand led to efficient catalysts for the hydroformylation of octene and other olefins in water. While the surfactants allowed the formation of micelles that dissolve both the catalyst and the alkene, thereby resulting in high olefin:rhodium ratios, the diphosphite provided a tight envelope about the catalytic centre able to drive the reaction towards the linear aldehydes. Best results in the hydroformylation of 1‐octene were obtained when using [tetra(p‐sulfonato)]‐(tetra‐n‐butoxy)‐calix[4]arene as surfactant. With this additive remarkable linear to branched aldehyde ratios of up to 62 were obtained, the corresponding activities being higher than those observed when operating in an organic solvent [turnover frequencies (TOFs) up to 630 mol(converted 1‐octene)⋅ mol(Rh)−1⋅h−1].  相似文献   

11.
三光气法制备均苯三甲酰氯   总被引:3,自引:0,他引:3  
常温下,采用三光气与均苯三甲酸在催化剂作用下制备均苯三甲酰氯(TMC),最佳收率可达88%。产品熔点为32.5~33.6℃,w(TMC)>99.2%,IR图谱与标准谱基本一致。通过对催化剂、溶剂和反应底物配比等影响因素的研究发现:(1)在常温下单一催化剂,如N,N-二甲基甲酰胺、吡啶、咪唑、三乙胺等不能让反应进行完全,收率<32%;而用复合催化剂,如吡啶/N,N-二甲基甲酰胺、咪唑/三乙胺等在常温下能反应完全,收率>60%。(2)溶剂的溶度参数与均苯三甲酰氯的溶度参数相差越小,反应速度越快。(3)反应底物配比n(三光气)/n(均苯三甲酸)<1.2时,几乎得不到产品,随着n(三光气)/n(均苯三甲酸)增大,收率增高;当n(三光气)/n(均苯三甲酸)>3后,其增大对产品收率影响不大。  相似文献   

12.
Free-of-loss Catalyst Recycling in the Hydroformylation of Higher Molecular Olefins by a Novel Process Technology In this paper a novel homogenous-heterogeneous procedure for the hydroformylation reaction of higher molecular olefins is presented, at which the reaction itself is homogeneously catalyzed and only after the reaction the catalyst complex is heterogenized only for separation. This procedure is achieved by using the lithium salt of triphenylphosphine monosulfonic acid (Li-TPPMS) as complex ligand for the hydroformylation catalyst and methanol as solubilizer. Li-TPPMS and its complexes with metal carbonyls are highly soluble in water and methanol, but completely insoluble in almost all other organic solvents. After the reaction the methanol is distilled off. The catalyst system becomes insoluble and can be separated from the reaction product by filtration or by extraction with water. The aqueous catalyst solution is evaporated to dryness and the catalyst system dissolved in methanol for a new reaction.  相似文献   

13.
During the last decades, the engineering of chemical processes has focused more and more on energy efficiency and reduction of climate‐changing emissions. Regarding the synthesis of aldehydes, the photocatalytic dehydrogenation of alkanes to olefins, using visible (sun) light, and the subsequent hydroformylation of such olefins with CO2 seem to be capable to achieve both targets. This work deals mainly with catalyst concepts for both reaction steps. Here, kinetic studies of the photocatalytic alkane dehydrogenation are presented, and the feasibility of hydroformylation using CO2 is described in a continuous gas phase reaction. The problems that have to be solved befoe the technical application are discussed and an economic and ecological evaluation for both processes is carried out.  相似文献   

14.
《分离科学与技术》2012,47(11):2609-2625
Abstract

Experimental results of the solubilization of olefins in hydroformylation model systems, comprising 1-dodecene and 1-tridecanal or 1-tetradecene and 1-pentadecanal, water, butanol, sodium dodecylsulfate (SDS), sodium dodecylbenzenesulfonate (SDBS), and/or tri(m-sulfofenyl)phosphine trisodium salt (TPPTS-Na) are presented. The selected systems were used for the hydroformylation of 1-dodecene and 1-tetradecene whereby high yields of aldehydes were obtained. After the reaction, the mixture spontaneously separated into an organic phase with the reaction products and an aqueous phase comprising the catalyst and excess phosphine ligand.  相似文献   

15.
Hydroformylation of formaldehyde to glycolaldehyde (GA),as a vital reaction in both direct and indirect process of syngas to ethylene glycol (EG),shows great advantages in the aspects of the process complex-ity and clean production.The hydroformylation of formaldehyde to GA is thermodynamically unfavour-able,requiring the development of highly efficient hydroformylation catalytic systems,appropriate reaction conditions and in-depth understanding of the reaction mechanisms.In this review,we have made a detailed summary on the reaction in terms of the reaction network,thermodynamics,metal com-plex catalysts (including central metals and ligands),reaction conditions (e.g.,temperature,pressure,formaldehyde source and solvent) and promoters.Furthermore,the reaction mechanisms,involving neu-tral and anionic complex in the catalytic cycle,have been summarized and followed by a discussion on the impact of the crucial intermediates on the reaction pathways and product distribution.A brief over-view of product separation and catalyst recovery has been presented in the final part.This review gives new insights into the factors that impact on the formaldehyde hydroformylation and reaction mecha-nisms,which helps to design more efficient catalytic systems and reaction processes for EG production via the hydroformylation route.  相似文献   

16.
The overall productivity of the aqueous biphasic hydroformylation of the castor oil‐derived methyl 10‐undecenoate is increased. To increase the reaction rate, the miscibility of water and the fatty compound is increased by addition of the green solvent 1‐butanol as co‐solvent. For the first time, the concentration of solvents, substrate, and product within the reaction process is experimentally examined in a biphasic system under 20 bar pressure of synthesis gas and 140 °C. A reactor to get samples of both phases is developed to determine the quarternary mixture of the reaction system presented in a four‐dimensional tetrahedron diagram. With the knowledge gained about the reaction and its drivers, it is possible to increase the efficiency of the reaction process reported so far. With simultaneously high reaction rates (turn over frequency = >5000 h?1), the space–time yield of the reaction reaches values of >120 g L?1h?1 and can be improved significantly without negatively affecting catalyst leaching. Practical Applications: Most polymers are made of petrochemicals. Here, the development of a highly efficient process for the formation of bifunctional molecules starting from technical grade methyl 10‐undecenoate made from castor oil in an aqueous biphasic reaction system is presented. By rhodium catalyzed hydroformylation, an aldehyde ester is formed which can be used to create alcohols, carboxylic acids, and amines. Subsequently, these molecules can be used as polymer precursors in polycondensation reactions.  相似文献   

17.
The concept of covalently connecting a catalytically active transition metal center with a water-soluble receptor (host molecule) makes a new type of supramolecular catalysis possible in which the features of molecular recognition, phase transfer catalysis and transition metal catalysis are combined in a single system. The first examples of this principle make use of the commercially available β-cyclodextrin (β-CD) as the receptor and rhodium complexes of diphosphanes as the catalytically active center, these being covalently connected to one another via a spacer. In competitive hydrogenation of certain olefins unusual degrees of substrate selectivity based on the molecular recognition are observed, not possible by conventional transition metal catalysts. The two-phase (H2O/organic) hydrogenation of nitro-aromatics also is a smooth process with these supramolecular catalysts. They also constitute an unusually active catalyst system for the selective hydroformylation of higher olefins such as 1-octene in a two-phase system.  相似文献   

18.
The hydroformylation of 10‐undecenenitrile ( 1 ) – a substrate readily prepared from renewable castor oil – in the presence of rhodium‐phosphane catalysts systems is reported. The corresponding linear aldehyde ( 2 ) can be prepared in high yields and regioselectivities with a (dicarbonyl)rhodium acetoacetonate‐biphephos [Rh(acac)(CO)2‐biphephos] catalyst. The hydroformylation process is accompanied by isomerization of 1 into internal isomers of undecenenitrile ( 1‐int ); yet, it is shown that the Rh‐biphephos catalyst effectively isomerizes back 1‐int into 1 , eventually allowing high conversions of 1 / 1‐int into 2 . Recycling of the catalyst by vacuum distillation under a controlled atmosphere was demonstrated over 4–5 runs, leading to high productivities up to 230,000 mol ( 2 )⋅mol (Rh)−1 and 5,750 mol ( 2 )⋅mol (biphephos)−1. Attempted recycling of the catalyst using a thermomorphic multicomponent solvent (TMS) phase‐separation procedure proved ineffective because the final product 2 and the Rh‐biphephos catalyst were always found in the same polar phase. Auto‐oxidation of the linear aldehyde 2 into the fatty 10‐cyano‐2‐methyldecanoic acid ( 5 ) proceeds readily upon exposure to air at room temperature, opening a new effective entry toward polyamide‐12.

  相似文献   


19.
离子液体作为一种新的绿色溶剂,日益受到人们的重视。本文从离子液体在氢甲酰化反应中的作用出发,介绍了离子液体/有机两相催化体系、离子液体/超临界二氧化碳催化体系、固定化离子液体多相催化体系等方面研究进展,并预示了离子液体在氢甲酰化反应中的应用前景。  相似文献   

20.
Ab initio quantum chemical computations have been done to determine the energetics and reaction pathways of hydroformylation of higher alkenes using a rhodium complex homogeneous catalyst. Calculation of fragments of the potential energy surfaces of the HRh(CO)(PPh3)3‐catalyzed hydroformylation of 1‐decene, 1‐dodecene, and styrene were performed by the restricted Hartree‐Fock method at the second‐order MØller‐Plesset (MP2) level of perturbation theory and basis set of 6‐31++G(d,p). Geometrically optimized structures of the intermediates and transition states were identified. Three generalized rate models were developed on the basis of above reaction path analysis as well as experimental findings reported in the literature. The kinetic and equilibrium parameters of the models were estimated by nonlinear least square regression of available literature data. The model based on H2‐oxidative addition fitted the data best; it predicts the conversion of all the alkenes quite satisfactorily with an average deviation of 7.6% and a maximum deviation of 13%. © 2009 American Institute of Chemical Engineers AIChE J, 2009  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号